Continuous catalytic conversion processes are common in the refining and petrochemical industry. The fluidized catalyst cracking of hydrocarbons is an important process for the production of lighter hydrocarbon components, and as such, it is an important process for the production of propylene. The fluidized catalytic cracking process continuously circulates a fluidized catalyst between a reactor and a regenerator.
Another route for the production of propylene can be obtained by the dehydrogenation of propane through catalytic dehydrogenation. The dehydrogenation catalysts generally comprise noble metal catalysts on acidic supports, such as alumina, or silica alumina, or zeolitic materials. However, the reaction is strongly endothermic, and requires a high temperature for the reaction to proceed at a satisfactory rate. The process also leads to coking of the catalyst, and deactivates the catalyst. The catalyst therefore needs to be regenerated on a regular basis after relatively short periods of operation, or residence, in the dehydrogenation reactor.
The production of propylene through dehydrogenation is an endothermic process and requires a substantial amount of additional heating to allow the process to proceed. The use of fuel fired charge heaters provides additional heat to the dehydrogenation reactors, but also results in problems such as fouling or coking of the charge heater tubes that can reduce the on-stream availability of the plant and increase the maintenance costs. Also, there is a loss of propylene yield that occurs due to non-selective cracking due to the thermal residence time in the heater and heater transfer line to the reactor.